A budget that does not create conflict between cost and performance.Point to point beams Bernard, what are you on?
Here is the device made for this job, goes off BEFORE entry.
I assume this is a vibration sensor and that the integral lens is for the LED indicator and not a PIR sensor lens.
If the device is moved slowly as could happen if the sky light was lifted up would this trigger an alarm. Also would it false alarm when heavy rain was falling on the sky light.
